Data from: Low genetic diversity and strong population structure shaped by anthropogenic habitat fragmentation in a critically endangered primate, Trachypithecus leucocephalus

Habitat fragmentation may strongly impact population genetic structure and reduce the genetic diversity and viability of small and isolated populations. The white-headed langur (Trachypithecus leucocephalus) is a critically endangered primate species living in a highly fragmented and human-modified habitat in southern China. We examined the population genetic structure and genetic diversity of the species and investigated the environmental and anthropogenic factors that may have shaped its population structure. We used 214 unique multi-locus genotypes from 41 social groups across the main distribution area of T. leucocephalus, and found strong genetic structure and significant genetic differentiation among local populations. Our landscape genetic analyses using a causal modelling framework suggest that a large habitat gap and geographical distance represent the primary landscape elements shaping genetic structure, yet high levels of genetic differentiation also exist between patches separated by a small habitat gap or road. This is the first comprehensive study that has evaluated the population genetic structure and diversity of T. leucocephalus using nuclear markers. Our results indicate strong negative impacts of anthropogenic land modifications and habitat fragmentation on primate genetic connectivity between forest patches. Our analyses suggest that two management units of the species could be defined, and indicate that habitat continuity should be enforced and restored to reduce genetic isolation and enhance population viability.

生境破碎化（habitat fragmentation）可对种群遗传结构产生强烈影响，并降低小型孤立种群的遗传多样性与生存能力。白头叶猴（Trachypithecus leucocephalus）是栖息于中国南方高度破碎化且受人类活动改造的生境中的极危灵长类物种。本研究针对该物种的种群遗传结构与遗传多样性展开调查，并探究了可能塑造其种群结构的环境与人为因素。我们利用白头叶猴主要分布区内41个社会群体的214个独特多位点基因型数据开展分析，发现当地种群间存在显著的遗传结构与强烈的遗传分化。本研究采用因果建模框架开展景观遗传学（landscape genetics）分析，结果显示：大型生境间隙与地理距离是塑造其遗传结构的主要景观因子，但即便被小型生境间隙或道路分隔的森林斑块间，也存在较高水平的遗传分化。本研究是首个利用核标记（nuclear markers）评估白头叶猴种群遗传结构与多样性的综合性研究。研究结果表明，人为土地改造与生境破碎化对灵长类动物森林斑块间的遗传连接性（genetic connectivity）具有强烈的负面影响。分析结果显示，该物种可划分为两个管理单元，同时提示应强化并恢复生境连通性，以降低遗传隔离程度并提升种群生存能力。